Dextromethorphan/guaifenesin/phenylephrine (By mouth)


Dextromethorphan (dex-troe-meth-OR-fan), Guaifenesin (gwye-FEN-e-sin), Phenylephrine (fen-il-EF-rin)

Relieves nasal congestion and cough due to respiratory tract infection.

Brand Name(s)

Phlemex, Phlemex-PE, Anextuss, Children's Mucinex Multi-Symptom Cold, Giltuss Pediatric, Dacex-DM, Mucinex Fast-Max Severe Congestion & Cough, Pres Gen, Rite Aid Tussin Cough and Cold Mucus Relief CF, Tussi-Pres, Robitussin Pediatric Cough & Cold CF, Z-Dex, G-Tusicof, Tusicof, TopCare Tussin CF

There may be other brand names for this medicine.

When This Medicine Should Not Be Used

You should not use this medicine if you have had an allergic reaction to guaifenesin, phenylephrine, or dextromethorphan. You should not use this medicine if you have high blood pressure or heart disease. You should not use this medicine if you are using MAO inhibitors such as Eldepryl®, Marplan®, Nardil®, or Parnate®. Do not give any over-the-counter (OTC) cough and cold medicine to a baby or child under 4 years old. Using these medicines in very young children might cause serious or possibly life-threatening side effects.

How to Use This Medicine

Capsule, Tablet, Long Acting Tablet, Liquid

  • Your doctor will tell you how much of this medicine to use and how often. Do not use more medicine or use it more often than your doctor tells you to.
  • It is best to take this medicine with food or milk.
  • Swallow the extended-release tablet whole. Do not crush, break, or chew it.

If a dose is missed:

  • This medicine needs to be given on a fixed schedule. If you miss a dose or forget to use your medicine, call your doctor or pharmacist for instructions.

How to Store and Dispose of This Medicine

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
  • Keep all medicine away from children and never share your medicine with anyone.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you are using MAO inhibitors such as Eldepryl®, Marplan®, Nardil®, or Parnate®. Tell your doctor if you are using antiyhypertensives such as guanethidine, methyldopa, mecamylamine, or reserpine.
  • Make sure your doctor knows if you are using tricyclic antidepressants such as amitriptyline, doxepin, nortriptyline, Elavil®, or Sinequan®.
  • Make sure your doctor knows if you are using beta-blockers such as atenolol, labetalol, metoprolol, nadolol, propranolol, timolol, Inderal®, or Toprol®.
  • Make sure your doctor knows about all the other medicines that you are using.

Warnings While Using This Medicine

  • Make sure your doctor knows if you are breastfeeding.
  • Make sure your doctor knows if you have diabetes, enlarged prostate, glaucoma, heart disease, high blood pressure, or an overactive thyroid.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Anxiety, restlessness, or nervousness.
  • Decrease in how much or how often you urinate.
  • Depression.
  • Fast heartbeat.
  • Headache or dizziness.
  • Lightheadedness.
  • Pale lips or pale skin color.
  • Seizures.
  • Trouble breathing.

If you notice these less serious side effects, talk with your doctor:

  • Nausea.
  • Weakness in your body.
  • Tremor.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last Reviewed on 06/12/2013

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